Stabilizer for large trucks or trailers



June 12, 1951 F. BlszANTz STABILIZER FOR LARGE TRUCKS 0R TRAILERS FiledNov.' 28 1945 3 Sheets-Sheet l v in INVENTOR FRED BISZANTZ "U VIIIATTORNEYS A m a June 12, 195] F. BlszANTz 2,556,610

STABILIZER FOR LARGE TRUCKS OR TRAILERS Filed NOV. 28, 1945 3Sheets-Sheet 2 INVENTOR FRED BISZANTZ ATTORNEYS F. BiszANTz 2,556,610

STABILIZER FOR LARG TRUCKS OR TRAILERS 5 Sheets--Sheei'l 3 28 Fla-7 Junel2, 1951 Filed Nov. 28, 1945 2e ,FIC-3.6

36 58 55 INVENTOR 72 73 FRED BlszANTz UWLMMLW ATToRNEYs Patented June12, 195i STABILIZER. FOR LARGE TRUCKS OR TRAILERS Fred Biszantz, Galion,Ohio, assignor to The Galion Metallic Vault Company, Galion, Ohio, a

corporation of Ohio Application November 28, 1945, Serial No. 631,238

8 Claims.

The present invention relates to vehicle structure and more especiallyto large trucks or trailers.

Trucks or trailers on which dump bodies have been mounted are used attimes for spreading stone or other heavy aggregate on roadways. Theroadways are not always level or even smooth, i. e. devoid of bumps,consequently these long bodies, when raised to an angle of from 30 to50, will sway sidewise to an alarming extent on sideling roadways ifthere are no means for stabilizing the frame or holding it nearly levelother than the usual springs. Y

The primary object of the invention is to pro vide an improved truck ortrailer structure, preferably in the form of an accessory than can beapplied to standard types of trucks or trailers and by which the frameof the truck or trailer is maintained level when the body is raisedthrough a considerable angle.

Another object is to provide an improved truck or trailer on which adump body is mounted for spreading stone and other heavy aggregate onroadways, and in which the frame of the truck or trailer is stabilizedto prevent sidewise sway during the dumping or spreading operation.

Still another object is to provide an improved dump truck or trailerwith an improved frame stabilizing accessory and in which the stabilizerdoes not interfere with the normal operation of the springs under thetruck in moving the truck to the work area.

A further object is to provide an improved stabilizer for a dump truckor trailer in which a hydraulic medium is employed for stabilizationpurposes andsuch medium is controlled by suitably positioned valves.

Another object is to provide a stabilizing mechanism of the typereferred to in which the hydraulic medium, the hydraulic cylinders andvalves are entirely independent of the ordinary hydraulic check or shockabsorber used on trucks.

Still anotherobject is to provide a stabilizer for dump trucks andtrailers of the hydraulic operating type and in which the pressure fluidis employed to lock the dump body in a predetermined position or at apredetermined angle during the dumping or spreading operation.

Other objects and features will be apparent as the specification isperused in connection with the accompanying drawings in which:

Figure 1 is an elevational view of a conventional dumping or spreadingtruck provided with the improved stabilizer accessory.

Figure 2 is an enlarged view looking from the lic motor (not shown).

rear end of the truck shown in Figure 1, but with the body and cabremoved and showing the rear view of the stabilizing mechanism.

Figure 3 is a fragmentary sectional view, partly in elevation, showingthe details of the structure by which the stabilizing cylinder accessoryis supported from the frame of the truck.

Figure 4 depicts the rear view of aconventional dumping truck providedwith the improved stabilizing mechanism, but before this mechanism hasbeen adjusted, and showing the position of the main frame, with the bodyand cab removed, when the truck is travelling over a sideling road.

Figure 5 is a view similar to Figure 4, but showing the manner in whichthe stabilizing mechanism can be operated to level the frame of thetruck notwithstanding a considerable slope of the ground over which thetruck is travelling.

Figures 6 to 9 inclusive, are vertical sectional views of the operatingcylinder and valve mechanism by which hydraulic power is supplied to thestabilizing plungers. The latter, also the piston valve and theoperating handle, is shown in elevation. The valves are depicted in thevarious iigures as being in different operating positions to produceproper sequence yof operation at the plunger.

Referring particularly to Figure 1, reference character I designates thecab of the dump truck, the body of which is generally indicated at 2.The truck has built-up iron sides and is provided at the rear end with adoor 3 which swings about a pivot 4. The bottom of the body is mountedon a plurality of transversely extending and longitudinally extendingU-shaped beams 5 welded or otherwise secured together to form a rigidframe. A lower forward compartment may contain a spare tire 6. A heavyplate l may extend downwardly from the body 2 to which is attachedsuitable mechanism indicated by the ribbed plate 8 for raising andlowering the body. This plate 8V is attached to a heavy crank arm 9pivoted to plate V8 at I0 and this arm is adapted to be swung in thevertical direction, preferably by hydraulic power furnished through apump and a hydrau- This pump is operated from the engine of the truckand controlled by suitable levers (not shown). The longitudinal framemembers 5 of the truck are provided at each Side, toward the rear, witha pair of heavy downwardly extending webs I I, pivoted at I2 to a pairof spaced U-shaped beams I3 which are secured to the main frame orplatform I4 of the truck.

Thus, by moving the operating handle which .5 controls the valvemechanism (not shown) of the hydraulic motor, the dump body 2 can beraised to any predetermined angle, usually between 30 and 50 dependingon the amount of incline necessary for the contents of the body 2 toslide rearwardly through the open door. The main frame or platform I4 ofthe truck is spring mounted at the rear end as indicated by the leafsprings I5 on the main rear axle housing I6. The spring mechanism I5 issecured to the main frame in the conventional manner.

The axle housing I5 is provided at the center with a differentialhousing I1 and the axle contained in these housings carries preferably apair of tires IB at each end, together with suitable brake mechanismindicated generally at I9.

When the housings I6 and I1 are supported from the main frame i4 solelythrough the leaf springs I5 as in a conventional truck and assuming thatthe truck is travelling a road which has L considerable slope, the mainframe I of the truck assumes practically the same transverse slope asthat of the road because the springs I5 oier little or noself-equalizlng effect. Such a position has been depicted in Figure 4,in which f it will be noted that the cross beam of the main frame is atsubstantially the same angle as the roadway. However, by the use of theimproved stabilizing mechanism which is about to be described, the mainframe I4 of the truck can be maintained in a strictly horizontal levelposition regardless of the slope o1" the road so that the sway of thebody 2 when in elevated or its down position can be substantiallyeliminated.

The stabilizing mechanism is indicated generally at 2G in Figures 2, 4and 5. Each stabilizer, of which there are preferably two per truck, issecured to the inner surface of the U-shaped beams I3. For this purpose,a pair of spaced heavy joists 2l extending between two cross framemembers may be employed. An angle iron 23 having side plates 24 oftriangular shape may be tted within the U-shaped beam I3 and securedthereto by screws 25. A round cap member 2&5 loosely receives the pistonrod 23 of the stabilizer, this cap member being swivelly connected ateach side as indicated at 21 to the triangular plates 24. The upper legof the triangular member 23 has an opening 29 therein which looselyreceives the rod 28. This opening 29 is somewhat larger than the size ofthe piston 23. This double swivel connection provides a certain amountof support to the upper part of the piston 28 and the cylinder 34, andat the same l time prevents any jamming eiiects when the ypiston moveswith respect to the cylinder. The cap 25 is provided with a swivel rod3E! extending diametrically across the flange of the cap and is looselyreceived by an extension 3| formed on the top of the cylinder 34. Thus,the cylinder 34 is adapted freely to pivot relative to its supportingbracket 23. The purpose of this universal joint will be apparent whenthe operation of the entire stabilizer has been explained.

The lower end of the cylinder 34 is left free so that it is entirelysupported from the rod or pin (it. However, the piston rod 28 isextended through the lower end of the cylinder and is swivelly connectedas indicated at 35 to a clamping device 3| which extends about thehousing I6. If the housing is split near the position of thedifferential, it may also be desirable to Vprovide additional clampingdevices 32 on each side of the clamp 3|.

drical element 31.

A valve mechanism indicated generally at 33 may be secured to thecylinder 34 for controlling the admission of pressure iiuid to thecylinder on opposite sides of the piston. The details of the valvemechanism and also of the cylinder and its contained piston, are shownin Figures 6 to 9 inclusive. As indicated in these figures, the cylindermay comprise a pair of end plates 35, 36 secured in any suitable mannerto a cylin- There is a large square boss or projection 38 extending fromthe cylindrical member 31 toward the rear of the truck to providefacility of operation. This projection, together with the cylindricalcasing 31, is provided with a number of passageways indicated at 39which terminate in a plurality of twin branches 4E, 4I, 42 and 43 toVform ports. A valve piston 44 extends vertically through the projection38 in a slidable manner, this piston having a series of grooves 45, 46and 41.

There are passageways 48, 49 and 5t on the opposite side of the pistonrod from the ports to 43 inclusive. These passageways are interconnectedthrough a common passageway 5I. Spring pressed check valves 52 areseated in the upper and lower portions of the passageway 5I to close ofithe ports y48 and 55 under certain circumstances. An ordinary ball check53 is positioned in the middle passageway 5I to close ofi port 49 whendesired. The lower end of the piston rod 44 is provided with a atportion 54 which carries a pin 55. This pin is adapted to slide in aslot 56 formed in an extension of a hand operated lever 51. The innerend of this lever is pivoted at 58 to vthe lower end plate 3E of thecylinder casing. The upper end of the ialve rod 44 is provided with anysuitable number of grooves 59, adjacent one another, and these groovesare adapted separately to receive a spring urged steel ball 60. Thus, bymoving the handle 51 in a vertical direction, the valve rod or stem 44can be moved upwardly to assume any one of four positions determined bythe entry of the ball G into one Vof the grooves 59. The compartment 5Ihas a cylindrical extension 6I directed away from the port 49 andcontained within a projection 52 formed integral with the boss 38. Apiston rod 63 is snugly, but slidably received by the opening 6I andthis rod terminatesA in a bifurcated yoke member 64. A pivot rod isvprovided in the yoke member 64 and a lever 66a is swingingly mounted onthe pivot. The projection 52 has a downwardly and outwardly extendinglug which also terminates in a bifurcated portion 61 and to which thelever 65a is pivotally secured as indicated at 68. Thus, by grasping theupper portion of the lever E6 and causing it to swing about its pivot68, the piston rod 63 can be reciprocated in the cylindrical opening 6Iso that the eiect of a force piston is obtained. It is apparent thatsuitable packing and if necessary, properly designed glands should beused at any place where there is a tendency to leak as indicated at 59.

The piston rod 28 is slidably carried by two openings at opposite endsof the cylinder 34 and threads 'Il are provided at an intermediateposition on the rod. Any'type of :dexible piston can be secured to therod 28 in any suitable manner. As typiiied lin the drawings, a centralsupport plate 1! of annular shape may be employed, this plate -servingto `carry at each side a cup shaped leather washer 12 held in positionby a clamp plate 13 vand an annular nut 'I4 which is received by thethreads 19. Thus, by tightening each of the nuts 14, the leather washersare compressed and caused to squeeze outwardly against the working faceof the casing 34. Suitable packing devices 16 may be provided at eachend of the casing to prevent leakage of fluid along the piston rod 28.

Operation of the stabilizing mechanism Assume that a truck equipped withthe improved stabilizer is travelling on a road which has considerableslant, as indicated in Figures 4 and 5, and the operator knows that whenthe truck body 2 is swung to its elevated position for spreading, adangerous sway will be encountered, he immediately stops the truck andeither visionally or by means of devices about to be described,determines the angle that the truck frame I4 is inclined with respect tothe horizontal plane. To assist in this operation, a spirit level 11 maybe provided on the truck frame from which the angle of inclination canbe roughly estimated. If desired, a pair of measuring bars 18 (Figure 2)may be pivoted to the frame as indicated at 19 and swung downwardlyagainst the housing I6 on each side of the differential housing I1.

There is provided a spirit level 11 secured to some convenient part ofthe truck frame at the rear end thereof so that the operator can tellwhen the truck body is substantially level. In case it is desired topreset the truck body to some angularity, the bars 18 may be availed offor indicating how much the truck body is tilted relative to the axle.

Assume, for example, that he finds it desirable to elevate that portionof the frame to the left as shown in Figure 4 and thus, to elongate thelength of piston rod projecting out of the bottom of the stabilizingcylinder 34. To do this, he ilrst obtains the proper setting of thevalve rod or stem 44 by operating the handle 51 to bring the secondnotch from the top of the valve rod into engagement with the ball Si) asshown in Figure 7. The operator then quickly moves the lever 66a to andfro, causing the small piston rod 63 to reciprocate within its cylinderB2.

Assuming that the cylinders 34 and all the passageways leading throughprojection 38 are filled with a fluid, such as oil, pressure ofconsiderable intensity is applied to the pressure iluid by the pistonrod 63. The grooves 45, 46 and 41 of the valve stem 44 are so relatedwith respect to one another and with respect to the adjacent ports thatin the position/of the valve stem shown in Figure 7, pressure fluid willpass through the compartment 5l, past the upper ball 52, through theport 48, the groove 45 of the valve stem, through the port 40 and theupper passageway 39 to the upper side of the main piston. The

pressure uid below this piston is exhaustedl through the lowerpassageway 3%, through the port 42 and the groove 46 of the valve stem,through the port 49, past the ball check 53 and from' there it is forcedby the piston 63 to the upper side of the main piston as explainedabove. Consequently, by rapidly swinging the lever 66 back and forth,the main piston generally indicated at B is caused to move downwardlywith respect to the main cylinder 34 and the piston rod 28 is caused toextend to a greater distance below the main cylinder. Inasmuch as thecasing 34 is effectively secured in the vertical direction with respectto the truck frame 5, a downward movement on the piston 23 will cause anupward movement of the frame 5 of the truck.

On the other hand, assume that the operator desires to lower the righthand end of the frame as shown in Figures 4 and 5, he operates thehandle 51 to move the valve stem 44 so as to cause the ball 60 to engagethe lowermost notch of the stem as shown in Figure 9. Under thesecircumstances, as the lever 66a is rapidly swung right and left pressureuid from the upper side of the piston 8o exhausts through the upperpassageway 39 to the port 4I, thence through the groove 46 past the ball53 into compartment 5l where the pressure exerted by the piston rod 63causes the fluid to force the lower ball 52 against its spring. Thefluid then passes through the port 50, through the groove 41 and thelower passageway 39 to the lower side of thepiston. As the pistonraises, the rod 28 is pulled upwardly and, therefore, reduces thedistance between the cylinder 34 and the clamp ring 3l of the axlehousing. Thus, the right hand end of the frame I4 is caused to movedownwardly. y

It is, therefore, seen that by properly manipulating the valve handle 51and providing a hand pump lever 6E, the distance between the cylinder 34and the rear axle housing of the truck can be adjusted in any desiredmanner. This adjust-v ment will be continued until the spirit level 11indicates thatthe frame, and therefore the truck body, is horizontal oron an even keel notwithstanding considerable slope in the roadway.

After having brought the frame to a horizontal level, it is desirablethat the adjustments or rather the position of the piston shall remainstrictly at its adjusted position while the truck is travelling over thesloping road. It will be understood that in the case of severe jolts thepiston rod 28 may have a tendency to move slightly even though no changein the position of the handle 51 has been made. For this reason, a holdposition of the piston is provided for which pressure is maintained onboth sides of the piston in its adjusted position and the pressure uidis locked in place.

Referring now to Figure 6, assuming that the lever 51 has beenpositioned downwardly so that the ball Se engages the top groove 5S, itwill be noted that the solid portions of the valve piston 44, i. e.those portions on opposite sides of the grooves 45, 4S and 41 now bridgethe ports 46, 4I, 42 and 43 so that the pressure fluid is trapped onboth sides of the piston 8i).

After the truck frame has been swung to a horizontal position by propermanipulation of the valve lever 51 and the latter is moved to the holdposition shown in Figure 6, the operator then proceeds to elevate thetruck to the required inclination and to move the truck over the groundin order to spread the contents of the truck. When the truck body hasbeen lowered from its dumping position at the end of the spreadingoperation, the truck leaves the work area and upon reaching levelground, the operator then moves valve lever 51 in the proper directionand operates the hand pump at lever I6 to swing the frame members 5 intoparallel position with respect to the axle housing. The spirit level 11or the measuring bars 18 may again be consulted to establish thisparallel or level position.

Inasmuch as any one of the valve conditions shown in Figures 6, '1 and 9may be still in effect after the time that the frame 5 has been broughtinto parallel relation with the rear housing I6, the piston rod 28obviously constitutes a rigid connection between the housing and theframe of the truck. Consequently, the function of the springs l5 mayhave been rendered useless in providing.

flexibility of support over the rear axle yduring the trip of the truckfrom the Work-area -to the supply area. It is, therefore, desirablecompletely to free the piston 28 of any locking or holding effect sothat the link connection between the frame and the housing will betemporarily broken.

This can be done by the use of a forward position of the valve stem 44,as shown in Figure 8, in which the stem is moved upwardly kby the handle5i until the ball 6G engages the third groove from the top of the stem.It will be noted under these conditions that there is a directconnection between the upper passageway Se through the Vport 4i, thegroove 45 and port '42, to the lower passageway 39. Thus, the upperrandlower surfaces of the piston Sii are directly in communication with oneanother and the piston rod 28 rides freely withinthe cylinder 34. Underthese conditions, there can be no interference with the springiness orflexibility accorded by the elements i5 since the elevating and loweringlink stabilizers are temporarily rendered inoperative.

It will be noted that the hydraulic system, inluding the valve mechanismforming the operating medium of each stabilizer, is completely closedand is entirely separate from any other hydraulic system, such ashydraulic shock absorbers or body elevating mechanism, that may be usedin the operation of the truck. By permitting the piston rod 28 to extendthrough both ends of the cylinder, there is no oil displacement and thecylinder will always be iull of pressure fluid and consequently, noother tank or reservoir will be required. Inasmuch as the upper part ofthe piston 28 may extend for considerable distance out of the cylinder34, depending on the length of the stabilizer link that is required, itmay be necessary to provide a non-freezing or jamming support .at thispoint and a structure similar to that shown in Figure 3 may be used toadvantage. As explained hereinbefore, a universal joint is affordedbetween the support of the piston 28 and the cylinder on the one handand the angle iron 23 on the other hand due to the presence of the twoswivels 2'! and 30, and the fact that the opening 29 is somewhat largerthan the size of the piston 28.

The cylinder can be filled with the pressure fluid, which is normallyoil, through either one of the screw plugs 8l, assuming that the valvestem 44 is in the correct position to provide accese to either one orboth of the passageways 39. Any leakage of fluid can obviously be madeup in the same manner or in any other suitable way, depending on theconstruction of the cylinder 34 and the presence of oil filling openingstherein.

From the foregoing, it is evident that I have disclosed an improvedstructure by which a dump or spreading truck or trailer can be set on aneven keel or in a horizontal position during the spreading operation,even in the case of sideling roadways having considerable slope. Thesidewise sway of the 'truck or trailer is completely eliminated by theuse of the stabilizers and there is also provision by which the ordinarysprings of the truck are still permitted to function when thestabilizers are not in active use. The stabilizers may constitute anaccessory which can be readily applied to all standard forms of dumpingor spreading trucks or trailers and the actuating piston and controlvalve and auxiliary elements may all be formed into a single integralunit in order to facilitate attachment to the truck. Due to thesmallness of the piston 63, it becomes a relatively simple matter tooperate the handlever 8 66 to obtain the necessary change in the lengthof the v'stabilizer links between the truck `frame and vthe rear axlehousing.

t will `be understood that I desire to comprehend within-my Ainventionsuch modifications as come within the scope of the claims and theinvention.

Having thusfully described my invention, what I claim as new and desireto secure by Letters Patent is:

l. In a truck having a pair of rear wheels, and an axle structurecarrying said wheels, a dump body, and spring means mounting said lbodyon said axle; a pair of lindependently manually operable hydraulicmechanisms for adjusting the angular relation between said body and saidaxle structure, each of said mechanisms comprising a pair of movableparts one of which is connected with said body and the other of which isconnected withfsaid axle structure, means selectively adjustable forpermitting free relative yreciprocation between said parts or forlocking said parts together, and means for adjusting the relativepositions of said parts.

2. In a truck having a pair of yrear wheels, and an axle structurecarrying said wheels, a dump body, and spring means mounting said bodyon said axle; a pair of independently manually operable hydraulicmechanisms for adjusting the angular relation between said body and saidaxle structure, each of said mechanisms comprising a pair of movableparts one of which is connected with said axle structure and the otherof which is connected with said body, means selectively adjustable forpermitting free relative reciprocation between said vparts or forlocking said parts together, and means for adjusting the relativepositions of said parts, said hydraulic mechanisms being mounted onopposite sides of the midpoint of said axle structure and body.

3. In a truck having a pair of rear wheels, an axle carrying saidwheels, a dump body, and spring means mounting said body on said axle,and a pair of independent devices for adjusting the angular relationbetween said body and axle, said devices each comprising a hydrauliccylinder and a piston rod within said cylinder, one of said cylindersand rod being connected with said body and the other with said axle, amanually operable hydraulic means associated with each said device forchanging the relative position of said lpiston rod Aand cylinder thereofand independently of the other device, said manually operable vhydraulicmeans including a pump for exchanging iluid between opposite ends ofsaid cylinder for bringing about movement of said piston rod relativethereto, and valve means selectively operable for entrapping fluid insaid cylinder for locking said piston rod in position relative theretoor for providing free ilow of uid between opposite ends of saidcylinder, whereby said cylinder and piston rod can reciprocaterelatively freely when'said body and axle move relatively due to theaction of said spring means.

4. In a truck having a pair of `rear wheels; an axle carrying saidwheels, a dump body, and

spring means mounting said body on said axle;

thereof, and a valve associated with each cylinder and selectivelyoperable for controlling the iiow of uid to and from opposite endsthereof to control the direction of movement of said piston rod relativeto its cylinder by operation of said manually operable hydraulic means,said valve also being operable for entrapping fluid in said cylinder forlocking said piston rod in any predetermined position relative theretoor for freely hydraulically connecting the opposite ends of saidcylinder to permit free relative reciprocation between said cylinder andthe piston rod therein.

5. In a truck having a pair of rear wheels, an axle carrying saidwheels, a dump body and spring' means mounting said body on said axle; apair of devices for adjusting the angular relation between said body andaxle, each said device comprising a cylinder pivotally mounted on saidbody, a piston rod within said cylinder and having one end pivotallysecured to said axle, a 1manually operable hydraulic pump on each saidcylinder operable for causing movement of the said piston rod therein,and a valve on each cylinder for controlling the direction of movementof the piston rod therein as brought about by actuation of theassociated pump, said valve also being adjustable for entrapping fluidin the said cylinder to lock the piston rod in position relative theretoand also having a position where the opposite ends of said cylinder areconnected together to permit free relative reciprocation between saidcylinder and the piston rod therein.

6. In a truck having a pair of rear wheels, an axle carrying saidwheels, a dump body, and spring means mounting said body on said axle, apair of independent hydraulic mechanisms disposed between said body andaxle on opposite sides of the center point thereof, each of saidmechanisms comprising a hydraulic cylinder swivelly connected with saidbody for pivoting movement relative thereto in two planes, a doubleacting piston having equal areas on its opposite faces within saidcylinder and pivotally connected with said axle, manually operablehydraulic pumping means on each cylinder for changing the position ofthe said Vpiston rod therein, and valve means on each cylinderhydraulically connected -between the said pump thereon and the oppositeends of the said cylinder and selectively adjustable for reversiblyconnecting said pump with the said faces of said piston, for entrappingfluid against said faces, or for hydraulically interconnecting saidfaces.

7. In a truck having a pair of rear wheels, an axle carrying saidwheels, a dump body, and spring means mounting said body on said axle; apair of self-contained hydraulic mechanisms disposed between said bodyand axle on opposite sides of the center point thereof, each of saidmechanisms comprising a cylinder pivotally carried by said body, apiston rod extending completely through said cylinder and having one endpivotally anchored to said axle, a piston on said rod in said cylinder,manually operable hydraulic pumping means on each cylinder for changingthe position of said piston and rod therein, and a valve on eachcylinder for connecting the opposite ends thereof alternately to thesuction and discharge sides yof the said pump on the cylinder, forhydraulically connecting the opposite of the said cylinders together,and for entrapping fluid in the said opposite ends.

8. In a stabilizer of the character described; a cylinder, means forpivotally mounting said cylinder von a truck body, a piston having itsopposite faces equal and reciprocal in said cylinder, a piston rodcarried by said piston and adapted for pivotal connection with an axle,said cylinder being formed with passageways leading to the opposite endsthereof, a manually operable pump associated with said passageways andoperable for causing a hydraulic medium in said cylinder to ow throughsaid passageways from one side of said piston to the other, and a valvein said cylinder for controlling said passageways, said valve beingselectively adjustable for reversibly connecting said pump with saidpassageways, for closing 01T said passageways to entrap fluid in theopposite ends of said cylinder, and for connecting said passagewaystogether to provide free passage of iiuid between opposite ends of saidcylinder.

FRED BISZANTZ.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 894,933 Benson Aug. 4, 19081,975,119 Oates Oct. 2, 1934 1,983,444 Dry Dec. 4, 1934 2,148,504Richter Feb. 28, 1939 2,235,136 Barrett Mar. 18, 1941 2,278,081 KramerMar. 31, 1942 2,306,284 Shonnard Deo. 22, 1942 2,324,587 Krogh July 20,1943 2,365,387 Briscoe Dec. 19, 1944 2,369,545 Dunn, Jr Feb. 13, 1945FOREIGN PATENTS Number Country Date 240,409 Switzerland June 1, 1946

